package edu.tsinghua.ddb.beans.queryTreeNode;

import edu.tsinghua.ddb.beans.Sqlet;

public class QTSelect {

}
/**


select
predicates
child node

project
targets
child node

union
child nodes

result set


SQL parse:
by-way convert all "not" to anti operator

decompose

1.merge predicates
by logic without dictionary

2.understand identities:
make all the objects in dictionary
justify the column type

3.rewrite
Sqlet to QueryTree
begin with from
	bottom leaf nodes
use where join predicates
	token = value is a reference to another column
assert only one node now
select one by one

4.shift
select to the very down
...




**/